toolkit/test/accessibility/MessageArea.java

   1 import java.awt.Font;
   2 import java.awt.Rectangle;
   3 import java.awt.Color;
   4 import java.awt.Graphics;
   5 import javax.swing.JScrollPane;
   6 import javax.swing.JTextArea;
   7 import javax.swing.JScrollBar;
   8
   9
  10
  11 /** A message area displays text in a scrollable text widget.  It is a
  12     singleton.  Other objects can access it directly to display messages.
  13 */
  14 public class MessageArea
  15     extends JScrollPane
  16 {
  17     public static synchronized MessageArea Instance ()
  18     {
  19         if (saInstance == null)
  20             saInstance = new MessageArea ();
  21         return saInstance;
  22     }
  23
  24
  25
  26
  27     /** Create a new message area.  This method is private because the class is
  28         a singleton and may therefore not be instanciated from the outside.
  29     */
  30     private MessageArea ()
  31     {
  32         maText = new JTextArea();
  33         maText.setBackground (new Color (255,250,240));
  34         maText.setFont (new Font ("Helvetica", Font.PLAIN, 9));
  35         setViewportView (maText);
  36         setVerticalScrollBarPolicy (JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);
  37         setHorizontalScrollBarPolicy (JScrollPane.HORIZONTAL_SCROLLBAR_ALWAYS);
  38
  39         printMessage (
  40             "class path is " + System.getProperty ("java.class.path") + "\n");
  41     }
  42
  43
  44
  45
  46     /** Show the given string at the end of the message area and scroll to make
  47         it visible.
  48     */
  49     public static synchronized void print (String aMessage)
  50     {
  51         print (0, aMessage);
  52     }
  53
  54
  55
  56
  57     /** Show the given string at the end of the message area and scroll to make
  58         it visible.  Indent the string as requested.
  59     */
  60     public static synchronized void print (int nIndentation, String aMessage)
  61     {
  62         while (nIndentation-- > 0)
  63             aMessage = " " + aMessage;
  64         Instance().printMessage(aMessage);
  65     }
  66
  67
  68
  69
  70     /** Show the given string at the end of the message area and scroll to make
  71         it visible.
  72     */
  73     public static void println (String aMessage)
  74     {
  75         println (0, aMessage);
  76     }
  77
  78
  79
  80
  81     /** Show the given string at the end of the message area and scroll to make
  82         it visible.
  83     */
  84     public static void println (int nIndentation, String aMessage)
  85     {
  86         print (nIndentation, aMessage+"\n");
  87     }
  88
  89
  90
  91
  92     public void paintComponent (Graphics g)
  93     {
  94         synchronized (g)
  95         {
  96             JScrollBar sb = getVerticalScrollBar();
  97             if (sb != null)
  98             {
  99                 int nScrollBarValue = sb.getMaximum() - sb.getVisibleAmount() - 1;
 100                 sb.setValue (nScrollBarValue);
 101             }
 102             super.paintComponent (g);
 103         }
 104     }
 105
 106
 107
 108
 109     /** Append the given string to the end of the text and scroll so that it
 110         becomes visible.  This is an internal method.  Use one of the static
 111         and public ones.
 112     */
 113     private synchronized void printMessage (String aMessage)
 114     {
 115         maText.append (aMessage);
 116     }
 117
 118
 119
 120
 121     private static MessageArea saInstance = null;
 122     private JTextArea maText;
 123 }